**6. Conclusions**

The available evidence suggests that no patient with NOA should be discouraged from attempting mTESE, based on the clinical and laboratory parameters that have been tested to date as candidate predictors of SSR. Azoospermic men with complete AZFc deletions and history of cryptorchidism may have better chances of SSR compared to those with idiopathic NOA, while the predictive role of KS on SSR is still debated. While serum FSH level and testis volume are hardly informative about the presence of residual foci of spermatogenesis in patients with NOA, it could be interesting to assess the predictive role of markers of intratesticular testosterone level (such as serum 17 OHP) on SSR. Future studies are also required to evaluate the feasibility of molecular markers in the seminal plasma, particularly non-coding RNAs, as markers of residual spermatogenesis in patients with NOA.

**Author Contributions:** E.C. drafted the manuscript; G.M.C. critically revised the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
